This is inflammation of the cervix, the entry to the uterus from the vagina (see Diagram — Female Genital System). It’s usually caused by STDs, Chlamydia and Gonorrhea, or maybe the poorly-understood bacteria Mycoplasma genitalium. Other causes include irritants like diaphragms, spermicides, latex condoms, sex toys, etc.
We diagnose cervicitis through a speculum on pelvic exam, when it looks red and inflamed. We identify Chlamydia and Gonorrhea by simple tests (see topic Vaginal Discharge).
Women may have bleeding between periods or after sex, though many cases have no symptoms at all. Still, the main danger is if the STD germ enters the uterus & moves up the Fallopian Tube, causing Pelvic Inflammatory Disease (PID). That can cause fever, a woman can become very sick, in rare cases even die. However, even if PID occurs with no symptoms (usually in the case of Chlamydia), it can cause permanent scarring of the Tube that leads to infertility.
Treatment is by antibiotics that kill the STD germ. Since results take a few days to return, medications are usually given to cover all possibilities.